Warm-up

• Imagine that you are given 25 germinating pea seeds that have been placed in boiling

water for 5 minutes. You place these seeds in a respirometer and collect data. Predict

the rate of oxygen consumption (i.e., cellular respiration) for these seeds, and explain your reasons.

Monday 10/29 Agenda

• Tutoring starts today!• Analysis in lab packet • Share inquiry findings• Take Lab QuizHomework –Photosynthesis poster and CH. 10 online

assignments due tomorrowOne more week to do test corrections

10/30 Agenda

• Chloroplast structure and up to slide 25 (15 min)

• Photosynthesis Light Reaction • Calvin Cycle Homework – Study poster for open-poster quiz tomorrowPrint and bring AP Lab 4 Photosynthesis

(from my website) tomorrow, don’t need to read yet

• ■Enduring Understandings• • 1B1: Organisms share many conserved core processes and

features that evolved and are widely distributed among organisms today.

• • 2A1: All living systems require constant input of free energy.• • 2A2: Organisms capture and store free energy for use in biological

processes.• • 2B3: Eukaryotic cells maintain internal membranes that partition

the cell into specialized regions (e.g., mitochondria).• • 4A2: The structure and function of subcellular components, and

their interactions, provide essential cellular processes.• • 4A6: Interactions among living systems and with their environment

result in the movement of matter and energy.

Standard Deviation and Standard Error for first part of lab

• Take each groups rates- find mean rate

• Calculate Standard Deviation from mean

• Calculate standard error

• Graph rates on bar graph

• Add standard error bars

Graph Average Rates with Error Bars

Lee, Richard E. “Using Microrespirometers to Measure O2 Consumption by Insects andSmall Invertebrates.” The American Biology Teacher, vol. 57, no. 5, 284–85, 1995..

Chloroplasts: The Sites of Photosynthesis in Plants

• Leaves are the major locations of photosynthesis

• Their green color is from chlorophyll, the green pigment within chloroplasts

• Chloroplasts are found mainly in cells of the mesophyll, the interior tissue of the leaf

• Each mesophyll cell contains 30–40 chloroplasts

© 2011 Pearson Education, Inc.

• CO2 enters and O2 exits the leaf through microscopic pores called stomata

• The chlorophyll is in the membranes of thylakoids (connected sacs in the chloroplast); thylakoids may be stacked in columns called grana

• Chloroplasts also contain stroma, a dense interior fluid

© 2011 Pearson Education, Inc.

Figure 10.4

Mesophyll

Leaf cross section

Chloroplasts Vein

Stomata

Chloroplast Mesophyllcell

CO2 O2

20 m

Outermembrane

IntermembranespaceInnermembrane

1 m

Thylakoidspace

ThylakoidGranumStroma

Let’s look at model

Photosynthesis as a Redox Process

• Photosynthesis reverses the direction of electron flow compared to respiration

• Photosynthesis is a redox process in which H2O is oxidized and CO2 is reduced

• Photosynthesis is an endergonic process; the energy boost is provided by light

© 2011 Pearson Education, Inc.

Figure 10.UN01

Energy 6 CO2 6 H2O C6 H12 O6 6 O2

becomes reduced

becomes oxidized

The Two Stages of Photosynthesis: A Preview• Photosynthesis consists of the light

reactions (the photo part) and Calvin cycle (the synthesis part)

• The light reactions (in the thylakoids)– Split H2O

– Release O2

– Reduce NADP+ to NADPH– Generate ATP from ADP by

photophosphorylation

© 2011 Pearson Education, Inc.

• The Calvin cycle (in the stroma) forms sugar from CO2, using ATP and NADPH

• The Calvin cycle begins with carbon fixation, incorporating CO2 into organic molecules

© 2011 Pearson Education, Inc.

Light

LightReactions

CalvinCycle

Chloroplast

[CH2O](sugar)

ATP

NADPH

NADP

ADP

+ P i

H2O CO2

O2

Figure 10.6-4

• While light travels as a wave, many of its properties are those of a discrete particle, the photon.– Photons are not tangible objects, but they do have fixed

quantities of energy and amount depends on wavelength.

(b) Action spectrum

(a) Absorptionspectra

Engelmann’sexperiment

(c)

Chloro-phyll a Chlorophyll b

Carotenoids

Wavelength of light (nm)

Ab

so

rpti

on

of

lig

ht

by

ch

loro

pla

st

pig

me

nts

Ra

te o

f p

ho

tos

yn

the

sis

(m

ea

su

red

by

O2

rele

as

e)

Aerobic bacteria

Filamentof alga

400 500 600 700

400 500 600 700

400 500 600 700

RESULTSFigure 10.10

• The action spectrum of photosynthesis was first demonstrated in 1883 by Theodor W. Engelmann

• In his experiment, he exposed different segments of a filamentous alga to different wavelengths

• Areas receiving wavelengths favorable to photosynthesis produced excess O2

• He used the growth of aerobic bacteria clustered along the alga as a measure of O2 production

© 2011 Pearson Education, Inc.

• Chlorophyll a is the main photosynthetic pigment• Accessory pigments, such as chlorophyll b,

broaden the spectrum used for photosynthesis• Accessory pigments called carotenoids absorb

excessive light that would damage chlorophyll

© 2011 Pearson Education, Inc.

• When a molecule absorbs a photon, one of that molecule’s electrons is elevated to an orbital with more potential energy.– The electron moves from its ground state to an

excited state.– The only photons that a molecule can absorb

are those whose energy matches exactly the energy difference between the ground state and excited state of this electron.

– Because this energy difference varies among atoms and molecules, a particular compound absorbs only photons corresponding to specific wavelengths.

– Thus, each pigment has a unique absorption spectrum.

• Excited electrons are unstable.

• Generally, they drop to their ground state in a billionth of a second, releasing heat energy.

• Some pigments, including chlorophyll, release a photon of light, in a process called fluorescence, as well as heat.

Fig. 10.10

Figure 10.12

Excitedstate

Heat

e

Photon(fluorescence)

Groundstate

PhotonChlorophyll

molecule

En

erg

y o

f el

ectr

on

(a) Excitation of isolated chlorophyll molecule (b) Fluorescence

Fig. 10.9

Figure 10.18

STROMA(low H concentration)

STROMA(low H concentration)

THYLAKOID SPACE(high H concentration)

Light

Photosystem II

Cytochromecomplex Photosystem I

Light

NADP

reductase

NADP + H

ToCalvinCycle

ATPsynthase

Thylakoidmembrane

2

1

3

NADPH

Fd

Pc

Pq

4 H+

4 H++2 H+

H+

ADP+P i

ATP

1/2

H2OO2

A Photosystem: A Reaction-Center Complex Associated with Light-

Harvesting Complexes• A photosystem consists of a reaction-center

complex (a type of protein complex) surrounded by light-harvesting complexes

• The light-harvesting complexes (pigment molecules bound to proteins) transfer the energy of photons to the reaction center

© 2011 Pearson Education, Inc.

Figure 10.13

(b) Structure of photosystem II(a) How a photosystem harvests light

Th

yla

ko

id m

em

bra

ne

Th

yla

ko

id m

em

bra

ne

PhotonPhotosystem STROMA

Light-harvestingcomplexes

Reaction-centercomplex

Primaryelectronacceptor

Transferof energy

Special pair ofchlorophyll amolecules

Pigmentmolecules

THYLAKOID SPACE(INTERIOR OF THYLAKOID)

Chlorophyll STROMA

Proteinsubunits THYLAKOID

SPACE

e

Each photosystem consists of chlorophylls, accessory pigments, and proteins. The black arrows represent photons being passed like a wave to reaction center chlorophylls that actually donate their electrons.

Figure 10.14-5

Cytochromecomplex

Primaryacceptor

Primaryacceptor

H2O

O2

2 H

+1/2

P680

Light

Pigmentmolecules

Photosystem II(PS II)

Photosystem I(PS I)

Pq

Pc

ATP

1

2

3

5

6

7

8

Electron transport chain

Electron

transport

chain

P700

Light

+ HNADP

NADPH

NADP

reductase

Fd

e

e

e

e

4

e

e

Linear Electron Flow

Photosystem II Photosystem I

Millmakes

ATP

ATP

NADPH

e

e

e

ee

e

e

Ph

oto

n

Ph

oto

n

Figure 10.15

Cyclic Electron Flow• Cyclic electron flow uses only photosystem I

and produces ATP, but not NADPH• No oxygen is released• Cyclic electron flow generates surplus ATP,

satisfying the higher demand in the Calvin cycle

© 2011 Pearson Education, Inc.

Figure 10.16

Photosystem I

Primaryacceptor

Cytochromecomplex

Fd

Pc

ATP

Primaryacceptor

Pq

Fd

NADPH

NADP

reductase

NADP

+ H

Photosystem II

A Comparison of Chemiosmosis in Chloroplasts and Mitochondria

• Chloroplasts and mitochondria generate ATP by chemiosmosis, but use different sources of energy

• Mitochondria transfer chemical energy from food to ATP; chloroplasts transform light energy into the chemical energy of ATP

• Spatial organization of chemiosmosis differs between chloroplasts and mitochondria but also shows similarities

© 2011 Pearson Education, Inc.

• In mitochondria, protons are pumped to the intermembrane space and drive ATP synthesis as they diffuse back into the mitochondrial matrix

• In chloroplasts, protons are pumped into the thylakoid space and drive ATP synthesis as they diffuse back into the stroma

© 2011 Pearson Education, Inc.

Mitochondrion Chloroplast

MITOCHONDRIONSTRUCTURE

CHLOROPLASTSTRUCTURE

Intermembranespace

Innermembrane

Matrix

Thylakoidspace

Thylakoidmembrane

Stroma

Electrontransport

chain

H Diffusion

ATPsynthase

H

ADP P iKey Higher [H ]

Lower [H ]

ATP

Figure 10.17

• ATP and NADPH are produced on the side facing the stroma, where the Calvin cycle takes place

• In summary, light reactions generate ATP and increase the potential energy of electrons by moving them from H2O to NADPH

© 2011 Pearson Education, Inc.

Let’s watch animation of Phase I

• http://www.mhhe.com/biosci/genbio/biolink/j_explorations/ch09expl.htm

Concept 10.3: The Calvin cycle uses the chemical energy of ATP and NADPH to reduce CO2 to sugar

© 2011 Pearson Education, Inc.

• Carbon enters the cycle as CO2 and leaves as a sugar named glyceraldehyde 3-phospate (G3P)

• For net synthesis of 1 G3P, the cycle must take place three times, fixing 3 molecules of CO2

• The Calvin cycle has three phases– Carbon fixation (catalyzed by rubisco)– Reduction

– Regeneration of the CO2 acceptor (RuBP)

• Carbon enters the cycle as CO2 and leaves as a sugar named glyceraldehyde 3-phospate (G3P)

• For net synthesis of 1 G3P, the cycle must take place three times, fixing 3 molecules of CO2

• The Calvin cycle has three phases– Carbon fixation (catalyzed by rubisco)– Reduction

– Regeneration of the CO2 acceptor (RuBP)

© 2011 Pearson Education, Inc.

Input

3 (Entering oneat a time)

CO2

Phase 1: Carbon fixation

Rubisco

3 P P

P6

Short-livedintermediate

3-Phosphoglycerate6

6 ADP

ATP

6 P P1,3-Bisphosphoglycerate

CalvinCycle

6 NADPH

6 NADP

6 P i

6 P

Phase 2: Reduction

Glyceraldehyde 3-phosphate(G3P)

P5G3P

ATP

3 ADP

Phase 3:Regeneration ofthe CO2 acceptor(RuBP)

3 P PRibulose bisphosphate

(RuBP)

1 PG3P

(a sugar)Output

Glucose andother organiccompounds

3

Figure 10.19-3

For every one net G3P, requires 9 ATP and 6 NADPH from the light reaction.

• In photosynthesis, the energy that enters the chloroplasts as sunlight becomes stored as chemical energy in organic compounds.

Photosynthesis is the biosphere’s metabolic foundation

- About 50% of the organic material made is consumed as fuel for cellular respiration in plant mitochondria.– Rest is stored or used to build other organic compounds.

• On a global scale, photosynthesis is the most important process to the welfare of life on Earth.– Each year photosynthesis synthesizes 160

billion metric tons of carbohydrate per year.

10/31 Agenda• Finish photosynthesis• Review posters while I check them • Photosynthesis quiz (20 minutes) – open poster• Statistical analysis - standard deviation and standard error (standard

error bars on graph) (20 min)– I check lab packet from yesterday while you work in groups

• Intro Lab 4 and assign cuvettes• http://www.phschool.com/science/biology_place/labbench/lab4/intro.

html

Homework – • Prelab worksheet for Lab 4, skip part A, be ready to do part B

tomorrow – Read Lab, part B only• Unit Test next Tuesday 11/6 covers chapters 6-10 – BE

STUDYING!!!!

11/1 Agenda• Intro and Set up 4B (25 min)

– Slides on spectrophotometer– Set up blanks together. Calibrate spec and review how to use.– Assign jobs – recorder, timekeeper, cuvette mixer, spec operator (all help setup)– Assign cuvettes – each group does one of the four plus an inquiry tube

• Inquiry choices = screens, colored light, acid, base, salt, ice etc.

• Run Lab 4B (20 min)– I check prelabs during this – make use of your wait time by setting up graph

• Clean up and share data (10 min)– Dump contents of cuvettes down the drains, then use test tube brush to clean

out. Dry with paper towel. Wipe sides down with Kimwipes and put back in flask in bucket.

Homework• Do 4B Analysis – all of Analysis should be done for me to check tomorrow,

including graph• Unit Test next Tuesday 11/6 covers chapters 6-10

– you should be putting in at least a half hour of study/review per night!!!

• When light meets matter, it may be reflected, transmitted, or absorbed.– Different pigments absorb photons of different

wavelengths.– A leaf looks green

because chlorophyll, the dominant pigment, absorbs red and blue light, while transmitting and reflecting green light.

Fig. 10.6

Whitelight

Refractingprism

Chlorophyllsolution

Photoelectrictube

Galvanometer

Slit moves topass lightof selectedwavelength.

Greenlight

High transmittance(low absorption):Chlorophyll absorbsvery little green light.

Bluelight

Low transmittance(high absorption):Chlorophyll absorbsmost blue light.

SPECTROPHOTOMETER TECHNIQUE

605 nm is wavelength absorbed by DPIP

Each year

• Make 3 copies of the next slide – put in separate powerpoint, have kids record data and email to them

Clean up and share data with your side of the room (5 min)Dump contents of cuvettes down the drains, then use test tube brush to clean out. Dry with paper towel. Wipe sides down with Kimwipes and put back in flask in bucket.

11/2 Agenda• Hand back quizzes• Quick review prelab• Analysis and post lab discussion – I check while you present (also

last lab packet)• Lab bench quiz for Lab 4

Homework – • Do conclusion only (use rubric) for Photosynthesis lab in your

notebook – due Monday• Unit Test next Tuesday 11/6 covers chapters 6-10 • Free response questions due Monday